A particle-hole model approach for hypernuclei

A particle-hole model is developed to describe the excitation spectrum of single lambda hypernuclei and the possible presence of collective effects is explored by making a comparison with the mean-field calculations. Results for the spectra of 12C, 16O, 40Ca, 90Zr and 208Pb single lambda hypernuclei are shown. The comparison with the available experimental data is satisfactory. We find that collective phenomena are much less important in hypernuclei than in ordinary nuclei.Comment: 24 pages, 5 eps figures, accepted for publication in Nucl. Phys.

Perilipin Overexpression in White Adipose Tissue Induces a Brown Fat-Like Phenotype

Background: Perilipin A (PeriA) exclusively locates on adipocyte lipid droplets and is essential for lipid storage and lipolysis. Previously, we reported that adipocyte specific overexpression of PeriA caused resistance to diet-induced obesity and resulted in improved insulin sensitivity. In order to better understand the biological basis for this observed phenotype, we performed additional studies in this transgenic mouse model. Methodology and Principal Findings: When compared to control animals, whole body energy expenditure was increased in the transgenic mice. Subsequently, we performed DNA microarray analysis and real-time PCR on white adipose tissue. Consistent with the metabolic chamber data, we observed increased expression of genes associated with fatty acid β-oxidation and heat production, and a decrease in the genes associated with lipid synthesis. Gene expression of Pgc1a, a regulator of fatty acid oxidation and Ucp1, a brown adipocyte specific protein, was increased in the white adipose tissue of the transgenic mice. This observation was subsequently verified by both Western blotting and histological examination. Expression of RIP140, a regulator of white adipocyte differentiation, and the lipid droplet protein FSP27 was decreased in the transgenic mice. Importantly, FSP27 has been shown to control gene expression of these crucial metabolic regulators. Overexpression of PeriA in 3T3-L1 adipocytes also reduced FSP27 expression and diminished lipid droplet size. Conclusions: These findings demonstrate that overexpression of PeriA in white adipocytes reduces lipid droplet size by decreasing FSP27 expression and thereby inducing a brown adipose tissue-like phenotype. Our data suggest that modulation of lipid droplet proteins in white adipocytes is a potential therapeutic strategy for the treatment of obesity and its related disorders

Postnatal nutrition environment reprograms renal DNA methylation patterns in offspring of maternal protein-restricted stroke-prone spontaneously hypertensive rats

Maternal malnutrition hampers the offspring health by manipulating the epigenome. Recent studies indicate that the changes in DNA methylation could be reversed by afterbirth nutrition supplementation. In this study, we used DNA methylation arrays to comprehensively investigate the DNA methylation status of the renal promoter regions and the effects of postnatal protein intake on DNA methylation. We fed stroke-prone spontaneously hypertensive (SHRSP) rat dams a normal diet or a low-protein diet during pregnancy, and their 4-week-old male offspring were fed a normal diet or a high−/low-protein diet for 2 weeks. We found that the methylation status of 2,395 differentially methylated DNA regions was reprogrammed, and 34 genes were reset by different levels of postnatal protein intake in the offspring. Among these genes, Adora2b, Trpc5, Ar, Xrcc2, and Atp1b1 are involved in renal disease and blood pressure regulation. Our findings indicate that postnatal nutritional interventions can potentially reprogram epigenetic changes, providing novel therapeutic and preventive epigenetic targets for salt-sensitive hypertension

Water vapor in the starburst galaxy NGC 253: A new nuclear maser?

22 GHz water vapor emission was observed toward the central region of the spiral starburst galaxy NGC 253. Monitoring observations with the 100-m telescope at Effelsberg and measurements with the BnC array of the VLA reveal three distinct velocity components, all of them blueshifted with respect to the systemic velocity. The main component arises from a region close to the dynamical center and is displaced by <1 arcsec from the putative nuclear continuum source. The bulk of this maser component is spread over an area not larger than 70 x 50 mas. Its radial velocity may be explained by masing gas that is part of a nuclear accretion disk or of a counterrotating kinematical subsystem or by gas that is entrained by the nuclear superwind or by an expanding supernova shell. A weaker feature, located 5 arcsec to the northeast, is likely related to an optically obscured site of massive star formation.Comment: 6 pages, 4 Postscript figures, A&A Main Journa

Excitonic nonlinear absorption in CdS nanocrystals studied using Z-scan technique

Irradiance dependence of excitonic nonlinear absorption in Cadmium Sulfide (CdS) nanocrystals has been studied by using Z-scan method with nanosecond laser pulses. The wavelength dependence of nonlinear absorption has also been measured near the excitonic transition of 1S(e)-1S3/2(h). We observe the saturable absorption, which can be described by a third-order and a fifth-order nonlinear process for both 3.0-nm-sized and 2.3-nm-sized CdS nanocrystals. The experimental results show that the excitonic nonlinear absorption of CdS nanocrystals is greatly enhanced with decreasing particle size. A two-level model is utilized to explain both irradiance and wavelength dependence of the excitonic nonlinearity.Comment: 24 pages, 6 figure

miRNA-296-5p and BOK in Pancreatic Cancer

Background/Aims: Pancreatic ductal adenocarcinoma (PDAC) is characterized by aggressive invasion, early metastasis, and resistance to chemotherapy, leading to a poor prognosis. To clarify the molecular mechanism of these malignant characteristics, we performed a genome-wide microRNA (miRNA) array analysis utilizing micro-cancer tissues from patients with unresectable PDAC (stage IV), obtained by endoscopic ultrasound-fine needle aspiration (EUS-FNA). Methods: The expression profiles of 2,042 miRNAs were determined using micro-cancer tissues from 13 patients with unresectable PDAC obtained by EUS-FNA. The relationship between individual miRNA levels and overall survival (OS) was analyzed. Possible target genes for miRNAs were bioinformatically analyzed using the online database miRDB. Pancreatic cancer cell lines PANC-1, MIA PaCa-2, and PK-8 were transfected with miRNA mimic or small interfering RNA, and cell invasion, epithelial-mesenchymal transition (EMT), and apoptosis markers were examined. miRNA and mRNA expressions were examined by quantitative polymerase chain reaction. Results: Of 2,042 miRNAs, the 10 that exhibited the lowest correlation coefficient (p ≤ 0.005) between miRNA expression level and OS among the patients were identified. The miRDB and expression analysis in cancer cell lines for the 10 miRNAs identified miR-296-5p and miR-1207-5p as biomarkers predictive of shorter survival (p < 0.0005). Bioinformative target gene analysis and transfection experiments with miRNA mimics showed that Bcl2-related ovarian killer (BOK), a pro-apoptotic gene, is a target for miR296-5p in pancreatic cancer cells; transfection of miR-296-5p mimic into PANC-1, MIA PaCa-2, and PK-8 cells resulted in significant suppression of BOK mRNA and protein expression. These transfectants showed significantly higher invasion capability compared with control cells, and knock down of BOK in pancreatic cancer cells similarly enhanced invasion capability. Transfectants of miR-296-5p mimic also exhibited aberrant expression of EMT markers, including vimentin and N-cadherin. Moreover, these transfectants showed a significantly lower apoptosis rate in response to 5-fluorouracil and gemcitabine with a decrease of BOK expression, suggesting a role of miR-296-5p in drug resistance. Conclusion: These results suggest that miR-296-5p is a useful biomarker for a poor prognosis in patients with PDAC, and that the miR-296-5p/BOK signaling axis plays an important role in cell invasion, drug resistance, and EMT in PDACs

NASA Glenn/AADC-Rolls Royce Collaborated to Measure Erosion Resistance on Coated Polymer Matrix Composites

Polymer matrix composites (PMCs) are increasingly used in aerospace and automotive applications because of their light weight and high strength-to-weight ratio relative to metals. However, a major drawback of PMCs is poor abrasion resistance, which restricts their use, especially at high temperatures. Simply applying a hard coating on PMCs to improve abrasion and erosion resistance is not effective since coating durability is short lived (ref. 1). Generally, PMCs have higher coefficients of thermal expansion than metallic or ceramic coatings have, and coating adhesion suffers because of poor interfacial adhesion strength. One technique commonly used to improve coating adhesion or durability is the use of bond coats that are interleaved between a coating and a substrate with vastly different coefficients of thermal expansion. An example of this remedy is the use of bondcoats for ceramic thermal barrier coatings on metallic turbine components (ref. 2). Prior collaborative research between the NASA Glenn Research Center and the Allison Advanced Development Company (AADC) demonstrated that bond coats sandwiched between PMCs and high-quality plasma-sprayed, erosion-resistant coatings substantially improved the erosion resistance of PMCs (ref. 3). One unresolved problem in this earlier collaboration was that there was no easy, accurate way to measure the coating erosion wear scar. Coating wear was determined by both profilometry and optical microscopy. Both techniques are time consuming. Wear measurement by optical microscopy requires sample destruction and does not provide a comprehensive measure of the entire wear volume. An even more subtle, yet critical, problem is that these erosion coatings contain two or more materials with different densities. Therefore, simply measuring specimen mass loss before and after erosion will not provide an accurate gauge for coating and/or substrate volume loss. By using a noncontact technique called scanning optical interferometry, which was recently developed at Glenn, researchers can accurately determine the wear performance of erosion-coated PMCs while preserving the sample. An example of this interferometry technique is shown in the preceding figure for an erosion-coated inlet guide vane from a Rolls Royce AE3007 regional gas turbine jet engine. Erosion was conducted with coated and uncoated PMC vanes, with the abrasive material moving at a velocity of 229 m/s at impingement angles of 20 and 90 degrees. The coatings for PMCs remarkably reduced the erosion volume loss by a factor of approximately 10. Currently, several erosion coatings for PMCs are being compared and downselected for engine testing at Rolls Royce

Characterization of Nkx6-2-Derived Neocortical Interneuron Lineages

Ventral telencephalic progenitors expressing the homeodomain transcription factor Nkx6-2 have been shown to give rise to a multitude of cortical interneuron subtypes usually associated with origin in either the medial ganglionic eminence or the caudal ganglionic eminence. The function of Nkx6-2 in directing the fate of those progenitors has, however, not been thoroughly analyzed. We used a combination of genetic inducible fate mapping and in vivo loss-of-function to analyze the requirement of Nkx6-2 in determining the fate of cortical interneurons. We have found that interneuron subtypes are born with a characteristic temporal pattern. Furthermore, we extend the characterization of interneurons from the Nkx6-2 lineage through the application of electrophysiological methods. Analysis of these populations in Nkx6-2 null mice suggests that there is a small and partially penetrant loss of delayed non-fast spiking somatostatin/calretinin double positive cortical interneurons in the absence of Nkx6-2 gene function

Expression determinants of mammalian argonaute proteins in mediating gene silencing

RNA interference occurs by two main processes: mRNA site-specific cleavage and non-cleavage-based mRNA degradation or translational repression. Site-specific cleavage is carried out by argonaute-2 (Ago2), while all four mammalian argonaute proteins (Ago1–Ago4) can carry out non-cleavage-mediated inhibition, suggesting that Ago1, Ago3 and Ago4 may have similar but potentially redundant functions. It has been observed that in mammalian tissues, expression of Ago3 and Ago4 is dramatically lower compared with Ago1; however, an optimization of the Ago3 and Ago4 coding sequences to include only the most common codon at each amino acid position was able to augment the expression of Ago3 and Ago4 to levels comparable to that of Ago1 and Ago2. Thus, we examined whether particular sequence features exist in the coding region of Ago3 and Ago4 that may prevent a high level of expression. Swapping specific sub-regions of wild-type and optimized Ago sequence identified the portion of the coding region (nucleotides 1–1163 for Ago-3 and 1–1494 for Ago-4) that is most influential for expression. This finding has implications for the evolutionary conservation of Ago proteins in the mammalian lineage and the biological role that potentially redundant Ago proteins may have